In a combustion apparatus using a solid fuel, in order to achieve stable ignition and flame holding, supplying a mixed fluid (a mixed fluid of the fuel and a carrier gas thereof) containing a sufficient concentration of fuel to a flame holding part of a burner outlet is required. As a conventional technology for concentrating the solid fuel inside the burner, there are Patent Documents 1 and 2 below.
Patent Document 1 discloses a pulverized coal burner which includes a pulverized coal pipe having a curved tube section and a straight tube section for injecting a mixed fluid of a solid fuel and a carrier gas thereof, wherein a throttle section for throttling a flow path nearer a central axis is provided at immediately after the curved tube section, and the mixed fluid is sprayed and burned in a furnace by applying a swirl to a flow of the fluid by a swirler before an outlet of the straight tube section.
Patent Document 2 discloses a pulverized coal burner 21 as illustrated in FIG. 21. In a pulverized coal supply pipe 29 having a curved tube section 25 and a straight tube section 22 for injecting a mixed fluid of a solid fuel and a carrier gas thereof, a liquid fuel injection pipe 28 is provided on a central axis of the straight tube section 22, a secondary air supply pipe 23 and a tertiary air supply pipe 24 are disposed around the pulverized coal supply pipe 29, and a secondary airflow and a tertiary airflow are supplied toward a furnace 13. Further, the above patent discloses a configuration in which a pulverized coal concentration in a circumferential direction is made uniform by providing a swirl vane 26 downstream of the flow of the mixed fluid in the curved tube section 25, and a swirl strength of the flow is reduced by installing a swirl degree adjustment vane 27 in the vicinity of a burner outlet, as well as ignitability of flame of the pulverized coal is improved by making the mixed fluid close to a straight flow.